A high fidelity loudspeaker system may include two or more different loudspeaker portions for propagating sounds of different frequency ranges. The highest frequency loudspeaker may be utilized, for example, to propagate sound between about 1.5 kHz and 20 kHz. Because of the directionality of higher frequency sounds, the horn which couples sounds from the high frequency voice coil or driver to the atmosphere, is typically much wider in the horizontal direction than along its vertical or height direction, to provide good horizontal dispersion of the sound to all areas of a room.
When such a high frequency horn is tested, several phenomena can be found to occur that detract from high fidelity sound propagation. One phenomenon is that there is a loss of output over a narrow band of frequencies. Another phenomenon is that there is a "ringing" or echo effect at certain frequencies, such as near the frequency at which the output is reduced. These phenomena are present especially in high frequency horns that must be of short length to be accommodated in a housing of moderate size.